Field of the Invention
The invention relates to a clothing, in particular for use in the press section of a machine for manufacturing a fibrous web, such as a paper, cardboard, or tissue web, including a base structure and at least one staple-fiber layer which is disposed on the base structure and is connected thereto, and to a method for manufacturing a clothing of this type.
Clothings in a multiplicity of shapes are to be found in a paper-making machine. Depending on their position, the clothings are assigned different tasks which, apart from supporting and guiding the paper web, in particular serve dewatering. The water which is present in the paper web and which in terms of quantity decreases as the paper web passes through the machine, has to be conveyed away in a suitable manner, without the paper web being damaged thereby or being subjected to marks by mechanical or hydraulic procedures during dewatering.
Gentle dewatering is of primary importance in particular in the press section, since the path toward smoothing of the paper web is already set here. After initial dewatering in the forming section, the paper web is not yet sufficiently dry so as to freely run through the machine, but depending on the scenario is usually guided and pressed on at least one or between two felts.
Accordingly, the requirements to be met by corresponding press felts in terms of the quality of the surface, of water absorption and water release capabilities, and in terms of permeability to air and water are very high.
Established press felts typically have a load-bearing base structure, one or a plurality of additional layers for reinforcing or improving the abovementioned properties, and one or a plurality of layers of staple fibers. The latter represent a bottleneck in production, since the staple-fiber layers may be numerous, on the one hand, and are subject to a multistage and in parts labor-intensive manufacturing process before they are connected to the base structure, on the other hand. This connection is performed by needling in which a needle matrix impinges on the staple-fiber layer which bears on the base structure and pulls the individual fibers into the base structure and therethrough and, on account thereof, enables a fixed connection between the base structure and the staple-fiber layers.
Modern machines for making paper or cardboard often have a large working width which may be up to 11 m. It is thus obvious that the clothings have to have a like width. However, manufacturing clothings in these dimensions is becoming ever more complex and more expensive. Apart from the width of the weaving machines, the width of the needling machines and thus the high investment costs are factors limiting production.
It is thus in the interest of the paper-machine operators and of the clothing industry to seek solutions for manufacturing clothings in a simpler and more cost-effective manner yet in any dimension.
Various attempts to this end have already been undertaken some time ago.
For example, it is known from DE102011007291A1 and from DE102008000915A1 to apply a reinforcement layer of a warp-knitted fabric or another non-woven planar textile in a cross-machine direction to a base structure and to piece together the individual pieces until the complete length of the base structure has been covered. The latter, however, here is configured in the usual manner in the full length and width of the clothing.
It is in particular disadvantageous here that the reinforcement layer cannot be used on its own but only in conjunction with a base structure, since the former does not offer sufficient stability. Moreover, the yarns are not crimped or are undulated, so that there is a risk of the structure being dissolved during use of the clothing.
A clothing which when viewed in the cross direction has a plurality of part-webs which in the longitudinal direction extend parallel with one another and are disposed beside one another, and the lateral peripheries of which are connected by way of connection means is known from EP1209283B1. Adjacent lateral peripheries here have a meandering profile with alternating protrusions and clearances. The part-webs are intermeshed by way of the protrusions and clearances.
In particular the length of the connection regions which, on account of the helical winding of the part-webs, extends across a multiple of the length of the paper-machine clothing, is to be seen as disadvantageous in this prior art. Manufacturing of such a felt is highly complex, both in relation to the factor of time as well as in relation to handling. Moreover, in the case of seam regions extending in the longitudinal machine direction there is always the risk that said seam regions under load expand in a variable manner and the felt is thus damaged, which may result in a higher tendency toward marking as well as in malfunctions right up to felt ruptures, posing a risk to the operating personnel and damaging downstream machine parts.
Furthermore, a paper-machine clothing which is manufactured from individual panels which have jigsaw-puzzle like protrusions and clearances and may be joined together is known from U.S. Pat. No. 4,842,905. The panels here may be extruded, punched, laminated, or manufactured by similarly suitable methods.
The complex manufacturing which requires many steps is disadvantageous in this prior art. Furthermore, the durability of the connections is questionable when only a small protrusion is available on a long edge. In turn, a plurality of protrusions are associated with increased manufacturing complexity of the individual panels. In general, it is difficult to manufacture a seam which operates without marking and with sufficient stability. The construction of the clothing previously mentioned has seams or connections, respectively, in a plurality of directions, i.e. the machine direction and the cross-machine direction, which further increase the tendency toward marking. The intersection points of the seams here represent particular weak spots, both in relation to stability as well as in relation to the tendency toward marking.